It is proposed to examine the oxidation of a variety of organic compounds, including polycyclic aromatic hydrocarbons, sterols, isoprenoids, and unsaturated fatty acid derivatives by chemical and enzymic means to determine whether hydroperoxide derivatives are formed as initial but transient intermediates in the ultimate formation of epoxide derivatives associated with chemical carcinogenicity. Incubations of organic substrates with a variety of hydroperoxides, with molecular oxygen, or with chemical or enzyme systems likely to form hydroperoxides will be carried out and hydroperoxide and epoxide derivatives formed will be detected chromatographically, isolated, and identified. In addition, organic hydroperoxides and epoxides not heretofore described will be prepared for eventual testing as carcinogens. In these ways it is sought to strengthen the concept that certain unsaturated organic compounds are carcinogenic by nature of their metabolic alteration following ingestion.